Lift truck



Jan. 14, "1930.

P. GROENKE LIFT TRUCK Filed Feb. "4, 1927 Patented Jan. 14, 1930 UNITED STATES PATENT OFFICE PAUL GROENKE, OF BERLIN, GERMANY, ASSIGNOR TO GRUNDMANN & KUHN, OI

BERLIN, GERMANY LIFT- TRUCK My invention relates to a truck having a stationary frame properly mounted on and supported by the axles, and a platform adapted to be raised and lowered, with relation to the said frame, by means of a sys- 1 tem of levers arranged and adapted to impart to the said platform a parallel lifting motion.

The object of my invention is to provide a truck of the character above indicated in which a hydraulic lifting device is employed for the purpose of raising and lowering the platform on the parallel guide principle, and which is extremely compact and simple in construction, efficient and reliable in opera, 16 tion, strong and durable, and which has important distinguishing characteristics of its own such as a system of interconnected bellcrank levers and a mechanism for imparting motion to the levers through the hydraulic 20 lifting device for the purpose in view.

According to the present'invention I provide on the frame of the truck a hydraulic lifting device having a reciprocable piston and a system of preferably three pairs of bell-crank levers pivotally interconnected by rods or link with certain of the bell-crank levers pivotally connected to suitable supports carrying the platform, and I pivotally connect one pair of the said bell-crank levers with the said piston by means of suitable members for the purpose in view.

Before proceeding to describe the construction which I have selected as best embodying my invention, I desire to have it understood that said construction is not the only embodiment of which the invention is capable, that a wide range of equivalents may be employed for the arts which I will show and describe hereinafter, and that the nhraseology which I have adopted, is for the purposeof description and not of limitation except where the sense absolutely requires it.

In the accompanying drawings forming a part of this specification, and showing for purposes of exemplification, a preferred form and manner in which the invention may be embodied and practised but without limiting the claimed invention to such illustrative instance:

Figure 1 is a side elevation showing my 165,946, and in Germany February 16, 1928.

invention as applied to a four-wheel truck or wagon and with the platform thereon in. its lowered position; Figure 2 is a similar view showing the platform in its raised position; Figure 3 illustrates, in side elevation, the hydraulic lifting device and the members employed for connectin the piston thereof with the one pair of be l-crank levers; and Figure 4 is. a front view of the said lifting device,

Where desirable the same reference symbolsare used in the different figures to denote corresponding parts.

In reducing my invention to practice I rovide in the frame d two transverse sha s e for the bell-crank levers 7", two such levers being mounted on each shaft, preferably near the ends thereof and adapted to rock or swing thereabout or therewith. Corresponding arms of the levers f are pivotally connected with each other in pairs by transverse rods or shafts g and the two shafts g of the system are interconnected by rods 7 in the manner of a parallel guide. The other arms of the four levers f are pivotally connected by means of transverse rods 0 or the like, with the ends of arms Z) fixed to the bottom face of the platform a so as to depend therefrom, and acting to support the same in both the lowered and the raised position.

In the embodiment shown the hydraulic lifting device i is located at the front end of the truck. The piston is of the lifting device is of the two stepped or bipartite type, but it may be of any other conventional construction since no claim is made to the particular construction thereof with the sole exception that the upper or free end of the piston is provided with a suitable transverse member such as a bridle Z, as shown, serving 90, as a means for the necessary connection with the bell-crank lever system.

As will be seen in Figures 1 and 2 two bellcrank levers m are fulcrumed on a transverse shaft or rod duly supported on the frame of 96 i the truck in 'the vicinity of the lifting device 2', and the front arms of the levers m are ivotally connected with the two arms of the hridle Z by means of slots or the like so that when the piston moves upwards, in conse- 100 quence of the action of the pumps 2" operated by the lever 11, the bridle Z will have the necessary liberty of connection. The hind arms of the two levers m are interconnected by a transverse shaft or rod n and the latter is pivotally connected with the shaft or rod 9 interconnecting the two arms of the front pair of bell-crank levers f, as will be clearly seen in Figures 1 and 2, the means emplo ed for thus connecting the two rods or sha ts n and g, being, in the embodiment shown, a pair of links 0.

It does not seem necessary to explain in detail the operation of the described mechanism, it is rather believed that it will be sufficient to state that, upon actuation of the lifting device 1', the rising piston thereof will cause, through the agency of the described lever system, the platform to rise from the down position shown in Figure 1 to the up position illustrated in Figure 2, and vice versa when the piston is allowed to go down.

What I claim is In a lift truck comprising fixed and movable platforms, the combination therewith of two pairs of bell-crank levers, each pair of levers pivoted at its fulcrum point to one of the platforms and at the ends of one of the lever arms to the other of said platforms, two rods connectingthe ends of the other arms of the bell-crank levers to each other, a hydraulic lifting device mounted vertically on the fixed platform and having a movable piston, a third pair of bell-crank levers pivoted to fulcrum on said fixed platform, the forward ends of the third pair of bell-crank levers being connected by a bridle to the movable piston and the rear ends of the third pair of bell-crank levers being connected by links to those arms of one .of the first mentioned pairs of bell-crank levers, which are interconnected by said rods.

In testimony whereof PAUL GROE 

